With their wide range of driver assistance systems, the new Audi A4 and A4 Avant are setting benchmarks for the class. Nearly all of the equipment has been completely redesigned or greatly enhanced in comparison to previous models. Some of the systems are standard features, whereas the optional solutions can be chosen individually or are available in the packages Parking, City and Tour.
All of the versions of the new models include the safety system Audi pre sense city as standard equipment. At speeds of up to 85 km/h (52.8 mph), the system scans the road for other vehicles and pedestrians using a windshield-mounted front camera with a range of up to 100 meters (328.1 ft). If there is the threat of a collision, the driver receives a series of warnings, and if necessary the car starts to apply the brakes fully. At speeds up to 40 km/h (24.9 ft), it can fully prevent accidents within the system limits. At higher speeds up to 85 km/h (52.8 mph), warnings and brake intervention can reduce the impact velocity.
The optional Audi pre sense basic works with information from a variety of different vehicle systems. Once it detects unstable driving conditions, it initiates preventive measures to protect the occupants. The front seat belts are electrically tightened, and the windows and sunroof are closed. The hazard lights are also activated.
If a collision cannot be prevented and an accident is inevitable, the multicollision brake assist system supports the driver with controlled application of the brakes. This can help to prevent the car from skidding, which prevents further collisions.
Another standard system in the new Audi A4 and A4 Avant is attention assist, a component of the driver information system. It analyses driver behavior and issues a warning when it detects that the driver is becoming inattentive. The adjustable speed limiter, a standard feature, can be set to a particular speed ranging from 30 to 250 km/h (18.6 to 155.3 mph) – a very helpful tool for maintaining speed within city limits, in construction areas, and so on.
Adaptive cruise control including traffic-jam assist
Amongst the optional systems, the key feature is the adaptive cruise control (ACC) Stop&Go including traffic-jam assist. It maintains a specified distance between the new Audi A4 and A4 Avant and the car ahead; the driver can choose one of five distances and use Audi drive select to adjust the rate of acceleration and control dynamics.
The system, which relies on the signals from the two front radar sensors and the camera, interacts with the S tronic and the tiptronic to cover the full range of speeds from 0 to 250 km/h (155.3 mph); in manual transmissions, it starts at 30 km/h (18.6 mph).
The ACC's Stop&Go function (only available with automatic transmissions) can brake the new Audi A4 models to a full stop, and at the driver's wish it can automatically resume driving again. When the system is deactivated, the distance display shows how far the car ahead is, and it warns drivers when they are tailgating. Its operating range is at speeds of 60 km/h (37.3 mph) and above.
Another function of the ACC, the traffic-jam assist, can take over steering at speeds of up to 65 km/h (40.4 mph) on well-developed roads when traffic is congested. The system uses the radar and ultrasound sensors as well as the front camera, guiding the car by gently adjusting the steering and following the traffic ahead within system limits. In doing so, the traffic-jam assist uses the lane markings and other vehicles on the road for orientation.
When the traffic-jam assist reaches its system limits – for example, when the traffic thins out or there is a sharp curve ahead – the driver has to take over again completely. The system provides warnings at different levels. As a final measure, it safely brings the A4 and A4 Avant to a full stop.
Thanks to the ACC, the Audi pre sense front safety system on board can prevent rear collisions or help minimize impact. In dangerous situations, the system gives the driver a variety of warnings to brake: visual and acoustic signals as well as a tap on the brakes. If the driver does not respond, the car first starts to brake, and simultaneously it closes the windows and the sunroof. As the only ones in their class, the new A4 models then decelerates as much as possible if the car in front of it is still moving. The system automatically tightens the seat belts. Audi pre sense front also works when the ACC is not running.
The predictive efficiency assistant
Another system that is unique in its class is the predictive efficiency assistant, which is available as part of the Tour assistance package. It works in close conjunction with the adaptive cruise control, the navigation system and the camera-based recognition of traffic signs. The preselected speed adapts to the road conditions by itself, e.g. the topography of the route, speed limits and the traffic ahead.
Even when the navigation function is not on, the predictive efficiency assistant uses the data from the route to keep the driver informed about situations which call for lower speed. The system recognizes curves, roundabouts, road junctions, gradients, city limits and speed limit signs – in many cases long before the driver sees them. A corresponding warning appears in the combination instrument and/or the Audi virtual cockpit and head-up display. If the assistant screen is active, detailed graphics can be seen.
If the driver wishes, the system can take over the freewheeling of the automatic transmission itself under certain conditions. This form of "coasting" is only activated if it can last for at least five seconds. When it ends, the car automatically accelerates to the speed the driver has selected if the ACC is activated. The predictive efficiency assistant can reduce fuel consumption on country roads by up to 10 percent.
Other systems in the Tour assistance system
The Audi active lane assist is available separately or as part of the Tour assistance system. At speeds of 65 km/h (40.4 mph) and above, it helps drivers stay in their lanes. It receives its signals primarily from the front camera, which detects lane markings. If the new Audi A4 and A4 Avant approach a marking when the driver has not switched on a turn signal, the system makes a gentle adjustment to the electromechanical power steering to bring the car back into its lane.
Using the MMI system, drivers can decide whether this support should be activated at all times or only take place before the lane marking is crossed. If they choose the early-correction mode, the system will guide the car back into the middle of the lane. There is also the optional setting of making the steering wheel vibrate as a signal.
The avoidance assist is yet another high-end feature in the Tour assistance system. It activates when the new Audi mid-sized models have to avoid an obstacle so as to prevent an accident. Within fractions of a second, it uses data transferred from the front camera, the ACC and radar sensors to calculate the distance of the car ahead as well as its width and degree of offset. Its first warning is a tap on the brakes to alert drivers to the potential danger. As soon as the driver starts steering, the system offers support with the necessary lane changes with controlled interventions to the power steering.
The turning assist is another Audi innovation that monitors oncoming traffic during left turns (on cars with left-hand drive). It has an operating range between 2 and 10 km/h (1.2 and 6.2 mph). In dangerous situations, it brings the car to a complete stop. The system becomes active in the background as soon as the driver turns on the left turn signal.
The camera-based traffic-sign recognition assist (also available separately) rounds out the Tour assistance system. It identifies many traffic signs, including digital displays, and shows them to the driver as graphics in the head-up display and instrument cluster. The driver can also opt for visual warnings when he or she exceeds the speed limit indicated on traffic signs.
The City assistance system
The options in the City assistance system include the lane-changing feature Audi side assist (also available separately). From speeds of 15 km/h (9.3 mph) and above, it supports drivers in changing lanes, using the two rear radar sensors which measure across a range some 70 meters (229.7 ft). If another vehicle approaches quickly or is in the blind spot, a warning LED in the housing of the appropriate side mirror lights up. If the driver turns on the turn signal anyway, the LED blinks brightly many times in succession.
Upon request, the Audi side assist can be complemented by integrating the Audi pre sense rear system. It warns about potential collisions from behind and takes preventive measures such as activating Audi pre sense basic. Furthermore, it makes the hazard lights blink rapidly as a way of warning traffic behind the car. It remains active in the background at every speed even if the Audi side assist is turned off (unless a trailer is in use).
The rear cross-traffic assist is activated when the parking assist is turned on. When this occurs, drivers who are slowly driving backwards (for example, while leaving a parking spot at right angles to the road) are warned about approaching vehicles in critical range. There are different levels of warnings: visual, acoustic and a short jolt of the brakes. The back radar sensors provide the necessary data.
The exit warning is activated when the new Audi A4 and Avant stop moving. If other vehicles are approaching from behind, it warns occupants as they open the doors. The system warns drivers by means of LED fiber optics in the inside door-opening mechanism (contour lighting). In situations that are assessed as dangerous, special high-performance red LEDs blink and light up. The exit warning stays on for approximately three minutes after the ignition is turned off.
Other systems complete the City assistance package: the acoustic and visual park system plus, which automatically activates when it detects an obstacle, and the reversing camera. Both systems are also available separately.
The parking assistance system
The Parking assistance system features the park assist (also available separately). With the help of twelve radar sensors, it helps maneuver the car into parking spaces that are parallel or at right angles to the road, which it identifies independently when driving at a moderate speed. Furthermore, it can make its own way out of parking spaces parallel to the road. All the driver has to do is accelerate, shift gears and brake.
The 360-degree cameras are the second component of the package. The MMI monitor displays different perspectives from the car's immediate surroundings, including a virtual view and 180 degree images from the front and rear. Guidelines make it easier to maneuver in reverse gear. The 360-degree cameras are especially helpful in dealing with parking spaces or driveways where visibility is poor, and the cameras are also useful together with the rear cross-traffic assist in the rear.
A fully equipped new Audi A4 or A4 Avant has some 90 control units on board, many of which exchange data with each other. This kind of tight-knit interaction, especially among the driver assistance systems, would not be possible without a brand new approach to the car's electronic architecture.
The new FlexRay bus system connects several control units with each other and guarantees extremely rapid and secure data transfer. The most important components are the engine, the automatic transmission, the central chassis control unit, electronic stabilization control (ESC), the power steering control unit, the adaptive cruise control Stop&Go including traffic-jam assist, the video camera and the safety computer which steers the safety systems.
There are other data networks in addition to the FlexRay bus. CAN (controller area network) buses connect some of the assistance systems such as the Audi side assist, 360 degree cameras and the air-conditioning system. Furthermore, they are part of the communication between the convenience functions, the infotainment components and the central display and control components, such as the MMI and Audi virtual cockpit.
LIN (local interconnect network) buses complement the CAN buses by operating less complex integrated systems such as interior lighting. The Bang & Olufsen sound system with 3D acoustics uses a MOST (media oriented systems transport) bus.
In these new Audi mid-sized models, the electric systems also contribute to the light vehicle weight: enhanced topology, new aluminum cables and an AGM battery lower the weight by six kilograms (13.2 lb) in comparison with the earlier model.
*The fuel consumption and CO2 emission figures of all models named above and available on the German market can be found in the list on the last page of this basic information.